The present invention relates to a housing and mounting arrangement for a thermal protector device which is used for protecting various electrical apparatus, such as ballasts for fluorescent lamps and electric motors.
The use of thermal protector devices with various types of electrical equipment is well known. Such devices are thermal sensors which are usually placed in series with the power lead to interrupt the supply of current to the electrical equipment when its temperature exceeds a certain unsafe level. In a typical application, for example a ballast transformer for a fluorescent lamp, such thermal protector is located in a housing which insulates it from contact with any current carrying parts of the transformer and placed in close proximity to a portion of the transformer, for example one of its windings, to sense its temperature. Normally, the thermal protector, which can be in a metal casing, is placed in direct contact with the transformer coil for direct sensing of the coil temperature. If the temperature becomes excessive, the protector opens and the supply of current to the transformer is terminated.
Various arrangements have been provided for holding the thermal protector in proximity to the electrical equipment. For example, in U.S. Pat. Nos. 5,126,510 to Bauer and 4,861,943 to Yarmark, an open ended housing of insulating material is provided. The thermal protector device is inserted into the housing open end until it abuts a stop within the housing. The housing is provided with spring-like fingers which snap onto a part of the electrical equipment, such as a metal plate, whose temperature is to be sensed with the bottom wall of the housing being against the metal plate. The two leads from the thermal protector extend through the housing open end in the same direction and are wired into the leads of the electrical apparatus.
While such arrangements are operative, they are somewhat expensive from the point of view of manufacture of a housing with the snap-in arrangement, the use of a metal plate to accept the snap-in fingers and the assembly of the housing to the plate.
In housings for thermal protector devices shown in patents such as Snider U.S. Pat. Nos. 3,537,052, Kandpal 4,061,935, Gibler 4,335,368, Hauser 4,734,602, Ubukata 4,791,329, Campolo 4,694,223 and Hoffass 4,887,063, the insulated housings are closed and are merely placed close to or against the element whose temperature is to be sensed.